1. Field of the Invention
The present invention relates to an apparatus for cleaning the interior of tubes in a heat exchanger tube bundle. More particularly, the present invention relates to an apparatus for simultaneously cleaning the interior of several tubes within a heat exchanger tube bundle without removing the tube bundle from the heat exchanger.
2. Description of Prior Art
Heat exchanger tube bundles are used for the transfer of heat from a fluid media passing through a series of conduits. During this process, carbonaceous and calcareous deposits will form on the interior of the individual tubes and debris and other dirt will collect on the surface of the individual tubes. Therefore, in order to maintain efficient operation, it is necessary to periodically clean the interior and exterior of the tubes.
One method of cleaning the interior of heat exchanger tubes includes the progressive insertion of a small diameter tube, known as a lance, into the heat exchanger tube and pumping high pressure water through the lance to clean the interior of the tube. The water pressure in the lance may easily exceed 10,000 psi and flow rates in excess of 100 gallons per minute. Early prior art devices called for the lance to be manually operated and advanced into the heat exchanger tube. It will be appreciated that the manual operation of a lance is unsatisfactory for a number of reasons. First, the operator is required to overcome the force of the water pressure when inserting the lance into the tube. Further, should the lance wall rupture, an operator may be injured by the high pressure water flow. Similarly, an operator may be injured by backsplash from the lance during the insertion of the lance into the tube. Lastly, the manual operation of a lance is time consuming and costly, as only one lance may be used in manual operations.
Various mechanical devices have been used in an effort to overcome the above deficiencies in cleaning the interior of heat exchanger tubes. U.S. Pat. No. 3,903,912 to Ice, Jr. et al. discloses a multiple lance cleaning system, including lance positioning and drive means and exposed lance tubes. However, the use of exposed lance tubes continues to pose a danger to an operator should a lance wall rupture. U.S. Pat. No. 3,817,262 to Caradeur et al. also discloses a multiple lance cleaning system having a lance positioner and drive system and exposed lance tubes. However, as in the Ice disclosure, the operator is still exposed to the danger of potential lance tube rupture.
U.S. Pat. No. 3,901,252 to Riebe discloses a multiple lance system including a lance drive and enclosed lance tubes, manifold and water lines. However, Riebe does not disclose a lance positioning system capable of readily positioning the lances and lance drive into a multitude of tubes within the heat exchanger bundle. U.S. Pat. No. 4,856,545 to Krajicek et al. disclosed a multi-lance tube cleaning system having a lance drive means, lance tubes and manifold, and multiple high pressure water lines within an enclosed structure. The disclosure called for the cleaning structure to be positioned by a crane mounted on a truck or by other mobile crane, tractor or skid. However, there are a number of disadvantages, i.e., as the lances are moved forward, the center of gravity of the structure may shift, which could result in misalignment and unnecessary stress on the lance tubes.
A significant disadvantage of the above described multi-lance tube bundle cleaners is the amount of space required by the tube bundle cleaning apparatus. The tube bundle cleaners disclosed have a framework extending at least the length of the tube lances which is positioned adjacent to the tube bundle. Typically, a very limited amount of space surrounds the heat exchanger, making it difficult either to remove the tube bundle for cleaning or to clean the tubes with a prior art tube bundle cleaning apparatus while the tube bundle is in the heat exchanger. Additionally, some tube bundles are vertically positioned in the heat exchanger making it very difficult to clean the tubes with a tube bundle cleaning apparatus, as disclosed in the above patents, while the tube bundle is in place.
Accordingly, there exists a need for an improved tube bundle cleaner which is sufficiently portable to allow tubes to be cleaned while in place in the heat exchanger, regardless of whether the tubes are in a horizontal or vertical position. Furthermore, there exists a need for a portable tube bundle cleaner which cleans multiple tubes, has a lance drive means, enclosed lances, and an independent means for positioning the lance cleaning system.